System and method for operating a heat engine from a closed circuit of refrigerant fluid allowing recovery of heat energy from an outer fluid

ABSTRACT

The present invention relates to a heat engine integrating a refrigerant fluid in a closed circuit and intended to undergo changes in pressure and temperature, characterized in that the circuit comprises at least:
         one evaporation tank ( 4 ) positioned in contact with a fluid, outside the engine, moving in a nozzle ( 3 ),   one liquefier ( 11 ) in contact with a fluid capable of absorbing heat and associated with a conduit allowing the liquefied refrigerant fluid to return into the tank ( 4 ), and   at least one power turbine ( 15 ), positioned between the liquefier ( 11 ) and the tank ( 4 ), and   one compressor ( 9 ) downstream from the tank ( 4 ) in the circuit and arranged for controlling the temperature of the refrigerant fluid by controlling the suction of the evaporated refrigerant fluid,
 
and in that the refrigerant fluid remains at a pressure and temperature of saturating vapor on the whole of the circuit.

The present invention relates to the field of heat engine systems and more particularly to the field of heat engine systems which involve a closed circuit of at least one refrigerant fluid, and with reduced heat losses.

Presently, short supply of fossil energies leads to orienting operation of engines towards renewable energies or towards so-called hybrid devices associating fuels and electric energy, but their performances or autonomy are reduced when they are adapted to our vehicles. Certain alternating engines operate by using coolant or refrigerant fluids. These fluids notably have the property of being capable of evaporating at low temperature when they are at atmospheric pressure (1 bar). These fluids currently used in cold-producing systems (air-conditioning, freezer, refrigerator, etc.) are generally selected for their large heat absorption property when they change state, passing from their liquid phase to their gas phase. The heat, which is then absorbed by the fluid, is called the latent vaporization heat. In a refrigerant circuit, in the same way as in a heat engine, the refrigerant fluid plays the role of a heat conveyor between a cold source and a hot source.

Document U.S. Pat. No. 3,124,696 proposes a solution that involves a refrigerant fluid moving in a conduit for feeding a turbine actuating a generator. The generator then provides an electric heating resistor which participates in heating up the refrigerant fluid in its conduit. However, the operation of such an engine shows several drawbacks. A first of these problems is that the provision of heat only has the effect of overheating the gas in the conduit without having an influence on the pressure so as to increase the power of the turbine. Another problem encountered is that of the conduction phenomenon of the heat provided by the electric resistance, which then heats up both the condenser and the gases that it receives. Moreover, it should be noted that an optimum operation of the engine taught by document U.S. Pat. No. 3,124,696 only allows operation in a closed circuit without producing external work.

The goal of the present invention is to propose a thermodynamically functional solution with which it is possible to get rid of at least one drawback of the prior art, and which will be notably able to operate independently of the combustion of any type of fossil energy or of an electric source.

This goal is achieved by means of a heat engine comprising at least one closed circuit integrating a refrigerant fluid capable of undergoing changes in pressure and temperature, characterized in that the closed circuit comprises at least:

-   -   one first portion forming an evaporation tank positioned so as         to be in contact with a fluid outside the motor, moving in a         nozzle intended for vaporizing the refrigerant fluid at a clean         evaporator,     -   one second portion forming a liquefier in contact with a fluid         capable of absorbing heat and intended for liquefying the         refrigerant fluid, at least one conduit allowing the liquefied         refrigerant fluid to flow back into the tank of the first         portion, and     -   one third portion, positioned between the first portion and the         second portion, comprising at least one power turbine actuated         by the movement of the evaporated refrigerant fluid in the         circuit, and     -   one compressor positioned downstream from the first portion         relatively to the direction of motion of the refrigerant fluid         in the circuit and arranged in order to control the temperature         of the refrigerant fluid at the output of at least one         evaporation tank by controlling the suction of the evaporated         refrigerant fluid,         and in that the refrigerant fluid participating in the heat         transfers remains maintained at a saturating vapor pressure and         at the corresponding temperature on the whole of the circuit.

According to an alternative embodiment, the heat engine is characterized in that the fluid outside the engine is an ambient gas, the first portion of the circuit ensures evaporation of the refrigerant fluid concomitantly with a lowering of the temperature of the outer fluid right down to a temperature strictly above the freezing or crystallization temperature of the water likely to be in suspension in the ambient gas, and in that the circuit also comprises at least:

-   -   one dehydrating filter positioned downstream from the first         portion of the circuit relatively to the direction of motion of         the ambient gas in the nozzle, in order to drive the gas, which         has carried out a heat transfer towards the refrigerant fluid of         the first portion of the circuit, and     -   a fourth portion of the circuit forming an evaporation tank         positioned so as to be in contact with the moving air in the         nozzle, intended to allow evaporation of the refrigerant fluid         at a clean evaporator while carrying out a heat transfer towards         the refrigerant fluid at temperatures below the freezing or         crystallization temperature of the water suspended in the         ambient gas, this fourth portion being positioned downstream         from the dehydrating filter relatively to the direction of         motion of the ambient gas in the nozzle.

According to another alternative embodiment, the heat engine is characterized in that the fluid capable of absorbing heat in the liquefier is formed by a coolant fluid moving in a clean closed circuit that allows absorption of heat of the refrigerant fluid at the liquefier on the one hand, and provision of heat to a refrigerant fluid intended to be evaporated at an evaporator on the other hand.

According to another alternative embodiment, the heat engine is characterized in that the fluid capable of absorbing heat in the liquefier is formed by the refrigerant fluid moving in a parallel portion of the circuit and flowing from a fourth or fifth portion of the circuit forming an evaporation tank positioned so as to be in contact with the fluid outside the engine, moving in the nozzle, intended to allow evaporation of the refrigerant fluid at a clean evaporator, this fourth or fifth portion being positioned downstream from the first portion of the circuit relatively to the direction of motion of the outside fluid in the nozzle, the refrigerant fluid evaporating at a temperature less than the temperature of the refrigerant fluid flowing from the reservoir of the first portion being set into motion by a compressor positioned downstream from the liquefier relatively to the direction of motion of the fluid in the circuit.

According to another alternative embodiment, the heat engine is characterized in that the engine integrates at least one auxiliary heating device for increasing the temperature of the refrigerant fluid at the outlet and/or at the inlet of at least one turbine and/or compressor, and in that the auxiliary heating device is associated with a device for injecting liquid refrigerant fluid in order to maintain a saturating vapor pressure and to avoid build-up of a dry vapor.

According to another alternative embodiment, the heat engine is characterized in that at least one component capable of operating with heat losses is positioned in an open adiabatic enclosure in the portion of the nozzle located upstream from at least the first portion of the circuit relatively to the direction of motion of the outer fluid in the nozzle.

According to another alternative embodiment, the heat engine is characterized in that the movement of the fluid, outside the engine, in the nozzle, involves a turbocompressor.

Another goal of the invention is to propose a device with which one of the alternatives of the method of the invention may be applied.

This goal is achieved by means of a method for operating a heat engine according to any of claims 1 to 7, characterized in that the method comprises cyclically:

-   -   a step for vaporizing the refrigerant fluid in a tank of a first         portion of the circuit subsequent to at least one heat transfer         from a fluid outside the engine,     -   a step for suction by a compressor of the refrigerant fluid         vaporized in a tank of a first portion of the circuit,     -   a step for actuating a power turbine by displacing the vaporized         refrigerant fluid in the circuit,     -   a step for liquefying the refrigerant fluid in the second         portion of the circuit forming the liquefier subsequent to at         least one heat transfer towards a fluid used as a coolant,     -   a step for returning the liquefied refrigerant fluid into a         reservoir of the first portion of the circuit.

According to an alternative embodiment, the method for operating a heat engine according to the invention is characterized in that, as the fluid s used as a coolant is the refrigerant fluid moving in a parallel portion of the circuit, the method also comprises:

-   -   a step for vaporizing the refrigerant fluid in a tank of a         fourth or fifth portion of the circuit subsequent to at least         one heat transfer from a fluid outside the engine concomitantly         with the step for vaporizing the refrigerant fluid in the first         portion of the circuit; vaporization being carried out at a         temperature less than that of the vaporization in the first         portion of the circuit,     -   a step for suction by the compressor of the refrigerant fluid         vaporized in a tank of a fourth or fifth portion of the circuit,     -   a step for absorption of heat from the refrigerant fluid being         liquefied in the liquefier, by the refrigerant fluid vaporized         in a tank of a fourth or fifth portion of the circuit,     -   a step for mixing, at the compressor, the refrigerant fluid         vaporized in a tank of a fourth or fifth portion of the circuit,         with the refrigerant fluid vaporized in another portion of the         circuit, in order to integrate the circuit of the vaporized         refrigerant fluid into the first portion of the circuit, and     -   a step for returning the liquefied refrigerant fluid into a tank         of the fourth or fifth portion of the circuit.

According to another alternative embodiment, the method for operating a heat engine according to the invention is characterized in that the method also comprises at least:

-   -   one step for heating the evaporated refrigerant fluid moving in         the circuit, and/or     -   one step for injecting liquefied refrigerant fluid into         evaporated refrigerant fluid moving in the circuit.

The invention, with all its characteristics and advantages, will become more clearly apparent upon reading the description made with reference to the appended drawings wherein:

FIG. 1 illustrates a diagram of a first embodiment of a heat engine according to the invention,

FIG. 2 illustrates a diagram of a second embodiment of a heat engine according to the invention.

It should be specified that in the present document, the terms “outer fluid” or “fluid outside the engine” relate to any ambient gas or liquid and more particularly to ambient air for earthbound or airborne use, and to water for an aquatic use of the heat engine of the invention.

It should be specified that in the present document the term “nozzle” designates any conduit, tube, duct with which the displacement of a fluid outside the engine set into motion may be oriented.

The present invention relates to a heat engine, the operation of which is based on the general principle of heat pumps, cooling devices or condensers-evaporators, the whole integrated into a device with which ambient heat of the air may be recovered in order to transform it into utilizable work, on the one hand, and controlled and recovered in order to utilize the heat losses usually due by exhaust, radiation, friction or conduction, by transforming them into work.

The present invention is based on the fundamental boiling principle according to which, when a fluid is vaporized, its vaporization temperature is strictly related to the pressure that surmounts it. Thus, the more the pressure surmounting the vaporized liquid will be lowered, the more its boiling temperature will be reduced and vice versa. Moreover, at constant pressure, providing heat to a liquid does not necessarily increase its temperature. This is such that, at a temperature and at a pressure related to each other, and specific to a liquid, the boiling temperature said liquid remains fixed whatever the provided heat and temperature increase, from the moment that this liquid is constantly present. Any additional provision of heat beyond its boiling temperature is thus entirely used for this phase transition from the liquid state to the gas state. Any increase in the provision of heat can only accelerate the rate of this transformation as long as the liquid to be vaporized is present. The boiling temperature can only vary with the pressure, which is exerted on the relevant liquid.

The heat engine according to the invention comprises a nozzle (3) into which a flow of fluid outside the engine is introduced (1) and set into motion either by the displacement of the engine mounted on a vehicle, or under the action of a turbocompressor (2). In the case of adaptation to an aquatic medium, the turbocompressor (2) is for example replaced by a hydraulic turbine, the helical propeller of a ship or the stream of a river. At this nozzle (3), the outer fluid forms the hot source of the engine by exchanging heat with the refrigerant fluid used in a closed circuit of the engine. Inside the circuit, the refrigerant fluid is maintained at a saturating vapor pressure and at the corresponding temperature. The changes in temperature and pressure, which the refrigerant fluid may undergo, thereby develop in parallel following the vaporization curve of the fluid. Moreover, the amounts of heat exchanged with the refrigerant fluid do not cause a phase transition of the fluid but are absorbed or restored as latent vaporization or liquefaction heats respectively. A turbogenerator (10) may be positioned at the outlet of the nozzle (3) in order to recover at least one portion of the energy possessed by the moving outer fluid flow.

The circuit in which the refrigerant fluid participates in conveying heat comprises a first portion (4) which forms an evaporation tank where a heat exchange is carried out between the outer fluid and the refrigerant fluid allowing vaporization of the refrigerant fluid. Following the direction of motion of the refrigerant fluid in its circuit, the portion (4) extends towards another portion of the circuit, called the third portion and formed by at least one compressor (6, 9), which sucks up the vaporized refrigerant fluid and compresses it in order to set it into motion in the circuit. From this compressor (9), the refrigerant fluid is sent towards a liquefier (11) while passing through at least one power turbine (15) with which work may be provided. The liquefier (11) is positioned at a second portion of the circuit. At this level, the refrigerant fluid performs a heat exchange with a coolant fluid so that at the outlet of the liquefier (11), the refrigerant fluid returns to a tank (16) from which it terminates its cycle by returning into the tank of the first portion (4) of the circuit.

According to a preferred embodiment, in the nozzle (3), the evaporation tank (4) of the first portion is positioned downstream from the turbocompressor (2) with respect to the direction of motion of the fluid outside the engine.

In the nozzle (3), several evaporation tanks (4, 31, 8) may be arranged so as to benefit from the hot source, which is the outer fluid, in different ranks of temperature. These different tanks (4, 31, 8), crossed by the outer fluid, respectively cover the surface of the nozzle on the whole of a portion perpendicular to the axis of motion of the fluid in this nozzle (3). The additional tanks (8, 31) form the fourth and fifth portions of the closed circuit of the refrigerant fluid which allow diversified use of the vaporized fluid depending on the temperature at which the fluid is vaporized at the outlet of the portion (8, 31). These different tanks (4, 8, 31) all communicate at their base via an underlying tank (5) fed from the outlet tank (16) of the liquefier (11), this underlying tank (5) being preferentially positioned along one of the edges of the nozzle (3).

According to a preferred embodiment, the tanks which form the fourth (8) and fifth (31) portions are positioned parallel to the tank of the first portion (4) and downstream from the latter relatively to the direction of motion of the outer fluid in the nozzle (3). This plurality of tanks is of interest for allowing a cold source to be produced for the engine on the one hand and in the case when the outer fluid is a gas, for allowing dehydration of the gas so that heat may be recovered at temperatures less than the freezing or crystallization temperatures of the water likely to be in suspension in the ambient gas on the other hand.

In the case of the example shown in FIG. 2, with the tank (4) of the first portion, heat may be recovered concomitantly upon lowering of the temperature of the outer fluid. This heat exchange is arranged in order to stop when the outer fluid reaches a temperature strictly above the freezing or crystallization temperature of the water likely to be in suspension in the outer fluid. With the tank (31) of the fifth portion of the circuit, heat may be recovered by providing heat reduction at a temperature substantially equal to the freezing or crystallization temperature of the water suspended in the outer fluid. Downstream from this tank (31) and upstream from the tank (8) of the fourth portion of the circuit relatively to the direction of motion of the outer fluid in the nozzle (3), a dehydrating filter (7) is positioned in order to absorb the water suspended in the ambient gas, the absorbed water is then discharged from the nozzle (3) through a suitable conduit. The heat transfer between the outer fluid and the tank (8) of the fourth portion of the circuit is carried out with a dry gas at temperatures less than the freezing or crystallization temperature of the water, and is therefore achieved without freezing or crystallization of the water interfering and/or altering the components of the engine.

Control of the temperature of the outer fluid during heat exchanges at each of the tanks (4, 8, 31) is achieved by controlling the suction of the vaporized refrigerant fluid in each tank. The larger the suction of the vaporized refrigerant fluid at a tank, the more the pressure surmounting the vaporized liquid will be lowered, the more the boiling temperature will decrease, the more the refrigerant fluid in the tank will be able to absorb heat provided by the outer fluid and the more the temperature of the outer fluid will decrease. For each tank (4, 8, 31), the vaporized refrigerant fluid is sucked up by a compressor (9, 32) according to a respective path in the circuit, before returning to a common compressor (6) for recovering the vaporized refrigerant fluids in the different tanks (4, 8, 31). The electrocompressor (6) sucks up the vapors of refrigerant fluid gradually as they form in the evaporation tanks (4, 8, 31), further accelerating the vaporization rate by the generated vacuum pressure. This compressor (6) is for example adjusted so that a pressure of 3.5 kg/cm² is maintained in the evaporation tank (4) in order to stabilize the corresponding boiling temperature. Also, the compressor (9) sucks up the vapors of refrigerant fluid formed by the provision of residual heat from the outer fluid flow. It is for example adjusted so that the vacuum pressure generated by its suction is stabilized to about 0.7 kg/cm², which corresponds to a Freon® boiling temperature of −27° C. for this pressure. Thus, by absorbing the refrigerant fluid vapors in one of the tanks (4, 8, 31) as soon as a desired pressure is obtained, at least one of the compressors (6, 9, 32) adjusts, for example via a pressostat, the pressure which will be exerted on the liquid refrigerant fluid of the tank. Whatever the temperature at which the refrigerant fluid is found in each of the evaporation tanks (4, 8, 31), the temperature at the outlet and the corresponding saturating vapor pressure are determined by the controlled suction of the refrigerant fluid vapors, independently of the temperature of the outer fluid moving in the nozzle (3).

In the non-limiting exemplary embodiment shown in FIG. 2, the refrigerant fluid used may be carbon dioxide gas which is an easily vaporizable gas at room temperature and just as well easily liquefiable around −27° C. This refrigerant fluid may be at a temperature of 30° C. and at a pressure of about 73 bars at the outlet of the tank of the first portion (4) of the circuit, at a temperature close to 1° C. and at a pressure of about 33 bars at the outlet of the tank of the fifth portion (31) of the circuit, and at a temperature of −30° C. and a pressure of about 13 bars at the outlet of the tank of the fourth portion (8) of the circuit. The fourth portion (8) may operate at negative temperatures by means of the presence of the dehydrating filter (7). By maintaining a temperature close to 1° C. at the tank of the fifth portion (31), the outer fluid is maintained at the lowest possible temperature so that its dehydration may always by carried out by the filter (7). At 31° C., the carbon dioxide already has a saturating vapor pressure of 73 kg/cm² and at −27° C., a liquefaction pressure of 21 kg/cm², which represents a pressure difference of 52 kg/cm², able to powerfully actuate a turbine (15) or a turbogenerator (22).

According to a particular embodiment, the suction of the vaporized refrigerant fluid in the tank involves a clean electrocompressor (32) positioned on the path of the circuit between the reservoir (31) of the fifth portion and the common compressor (6) which collects vaporized refrigerant fluids from the different tanks (4, 8, 31).

At the condenser/liquefier (11), the compressed refrigerant fluid from a power turbine (15), where it has lost a portion of its energy as work, further has at the outlet of the latter, a relatively large amount of heat which may be abandoned at a cold source, according to Carnot's principle. The refrigerant fluid thus performs a heat transfer with a coolant fluid. During this step, the refrigerant fluid abandons the same amount of heat as that required for its transformation into a gas. According to a first embodiment shown in FIG. 1, appended in the enclosure, the coolant fluid flows in a closed circuit which is specific to it, where it is set into motion by a pump (17). In this type of assembly, the coolant fluid may for example be glycolated water. The coolant fluid recovers the heat from the refrigerant fluid at the liquefier (11) in order to transfer it at an evaporator (18) which returns the heat at the refrigerant fluid moving in one of the compressors (6, 9, 32) or at the power turbine (15). The coolant fluid thereby forms a continuous stream between the liquefier (11) and the evaporator (18). According to another embodiment shown in FIG. 2, the coolant fluid used is the evaporated refrigerant fluid in one of the tanks of the fourth or fifth portion of the circuit. The coolant fluid is preferentially the evaporated refrigerant fluid at the lowest temperature, in this case at negative temperatures. This refrigerant fluid intended to play the role of a coolant fluid is sucked up by at least one the compressors (6, 9, 32). However, the path followed by this refrigerant fluid at the outlet of the tank (8) of the fourth portion of the circuit passes through the liquefier (11) where the liquefaction heat is recovered, before opening out at one of the compressors (6, 9, 32) in order to return to the other refrigerant fluid vapors in the circuit.

In each of both embodiments proposed, a portion of the liquefied refrigerant fluid at the liquefier (11) is recovered in a tank (16) and may not return into the evaporation tanks of the first (4), fourth (8) and fifth (31) portions of the circuit via the underlying tank (5), but may return to a tank (30) which feeds an evaporator (18) at which the evaporated refrigerant fluid directly feeds, notably by suction, a pressure compressor (6). Fast vaporization of the refrigerant fluid borrows its heat from the coolant fluid which is cooled right down to the temperature corresponding to the pressure generated by the suction. This pressure may for example be 1.86 kg/cm² for a temperature of −15° C., or even 0.7 kg/cm² for a temperature of −27° C. In the case of the first embodiment shown in FIG. 1, with the evaporator (18), it is notably possible to recover the heat which the coolant fluid has absorbed at the liquefier (11) on the one hand and to reuse this heat for maintaining the evaporated refrigerant fluid in the circuit on the other hand.

According to a preferred embodiment, at least one component of the device of the engine, likely to have heat losses, is positioned in an adiabatic enclosure (20) with an aperture which opens out in the nozzle (3), upstream from the tanks (4, 8, 31) of the first, fourth, and fifth portions of the circuit relatively to the direction of motion of the outer fluid in the nozzle (3), the other components may be positioned, in an auxiliary compartment (19), in the nozzle (3), also upstream from the tanks (4, 8, 31) of the first, fourth, and fifth portions of the circuit relatively to the direction of motion of the outer fluid in the nozzle (3). According to a particular embodiment shown in FIGS. 1 and 2, the liquefier (11) and the evaporator are positioned in the adiabatic enclosure (20). With this particular arrangement, it is possible to obtain an optimum limitation of the heat losses and their recovery in order to heat up the outer fluid in motion before the latter enters in contact with at least any of the evaporation tanks (4, 8, 31).

According to a particular embodiment, the heat engine may integrate one or more auxiliary heaters (13) with which the refrigerant fluid moving in the circuit may be heated up. During their operation, these auxiliary heaters (13) increase the temperature of the refrigerant liquid so that the vaporized refrigerant liquid forms a dry vapor. In order to maintain a saturating vapor pressure in the circuit, an amount of liquid refrigerant fluid is injected at the portion of the circuit where the heating up is carried out by the auxiliary heater (13), thus increasing the vapor pressure which becomes saturating concomitantly with its cooling, this notably allowing the refrigerant liquid to be brought closer to its liquefaction point. The injector of liquid refrigerant fluid is fed with fluid from the portion of the circuit located downstream from the liquefier (11), for example from the tank (16) or the tank (30) as shown in FIG. 2. At least one auxiliary heater (13) is strategically positioned for heating up the refrigerant fluid at the outlet of at least one compressor (6, 9, 32) and/or at the inlet of the power turbine (15). Another auxiliary heater may be positioned at the tank (30) which feeds the evaporator (18) with refrigerant fluid. These auxiliary heaters (13) may be formed by electric resistors for example powered by a circuit derived from the power turbine, or by an auxiliary internal combustion engine (33), the provided heat of which passes into at least one sleeve which surrounds a portion of the circuit, for example at a chamber (12), or in the conduits which pass through one (5) or more tanks in order to participate in heating up the refrigerant fluid. According to an embodiment, shown in FIG. 2 provided in the enclosure herein, the heat produced by the internal combustion engine (33) is directed through feed Is conduits capable of being handled by valves. With these conduits, it is thereby possible to supply heat to one or more strategic points of the circuit of the refrigerant fluid at sleeves, positioned for example between the compressor (6) and the power turbine (15), and then to feed a conduit which participates in heating up the underlying tank (5). An auxiliary conduit also allows a sleeve to be fed at the tank (30) of the evaporator (18). Further, the internal combustion engine (33) is positioned in the nozzle (3) upstream from the different evaporation tanks (4, 8, 31) relatively to the direction of motion of the outer fluid so that the heat lost by this engine is transferred to the outer fluid so as to be used as a heat source for evaporation at the tanks (4, 8, 31).

According to a particular embodiment shown in the exemplary embodiment of FIG. 1, the heat engine of the invention may be associated with an auxiliary device capable of operating with a liquid outer fluid such as for example water, set into motion by a compressor. This auxiliary device comprises in its front portion, relatively to the direction of the flow of the moving outer fluid, an enclosure (24) of a substantially tubular shape embodying in its central portion a conduit integrating a tubular evaporator (23) in which the outer liquid is moved, on the one hand and in its peripheral portion which surrounds the central portion, a tank with an overlying portion (25) and an underlying portion (29) comprising refrigerant fluid on the other hand. In the portion of the auxiliary device located towards the rear, relatively to the direction of flow of the liquid outer fluid in motion, the tubular evaporator (23) of the central portion extends with a conduit which deflects the fluid towards the outside of the device, whilst the peripheral portion extends towards a turbogenerator (27), which comprises a turbine (26) feeding a generator, and then returns to a condensation tank (28) positioned in the nozzle (3). Thus, the refrigerant fluid vaporized in the front portion of the enclosure (24) by exchanging heat from the outer fluid at the tubular evaporator (23), will generate a movement which actuates the turbine (26). At the condensation tank (28), the refrigerant fluid is liquefied. To do this, the condensation tank (28) is positioned in the nozzle (3) downstream from the evaporation tanks (4, 8, 31) relatively to the direction of flow of the outer fluid in the nozzle. With this positioning, it is possible to benefit from the cooled outer fluid upon exchanging heat with the evaporation tanks (4, 8, 31) located upstream, in order to recover the heat of the refrigerant fluid stemming from the auxiliary device and being liquefied in the condensation tank (28). The outlet of this condensation tank (28) extends with a conduit which ensures the return of the refrigerant fluid into the tank (25, 29) of the front portion of the device.

At the nozzle (3) outlet, the outer fluid may escape at negative temperatures, for example of the order of −27° C. In a particular embodiment, this ice-cold flow may be recovered at a sufficiently large tubing bundle positioned in the liquefier (11) across the discharge flow of the refrigerant fluid vapors from the turbine (15).

At a much larger dimensional scale, this heat engine may be adapted to a nuclear or thermal power plant with the purpose of increasing the yield and the power. Indeed, the ice-cold outer fluid flow from the nozzle (3) may intervene in a process for cooling and liquefying the vapor from the turbines of the power plant, as a replacement for the water of a river or for the gigantic size of the present cooling towers.

It will be obvious for those skilled in the art that the present invention allows embodiments under many other specific forms without departing from the field of application of the invention as claimed. Therefore, the present embodiments have to be considered as an illustration but may be changed in the field defined by the scope of the appended claims. 

1. A heat engine comprising at least one closed circuit integrating a refrigerant fluid capable of undergoing changes in pressure and temperature, the closed circuit comprises at least: one first portion forming an evaporation tank positioned so as to be in contact with a fluid, outside the engine, moving in a nozzle, intended to allow evaporation of the refrigerant fluid at a clean evaporator, one second portion forming a liquefier in contact with a fluid capable of absorbing heat and intended to allow liquefaction of the refrigerant fluid, at least one conduit allowing the liquefied refrigerant fluid to return into the tank of the first portion, and one third portion, positioned between the first portion and the second portion, comprising at least one power turbine actuated by the movement of the evaporated refrigerant fluid in the circuit, and one compressor positioned downstream from the first portion relatively to the direction of motion of the refrigerant fluid in the circuit and arranged in order to control the temperature of the refrigerant fluid at the outlet of at least one evaporation tank while controlling the suction of the evaporated refrigerant fluid, and in that the refrigerant fluid participating in heat transfer remains maintained at a saturating vapor pressure and at the corresponding temperature on the whole of the circuit.
 2. The heat engine according to claim 1, the fluid outside the engine is an ambient gas, the first portion of the circuit ensuring evaporation of the refrigerant fluid concomitantly with a lowering of the temperature of the outer fluid right down to a temperature strictly above the freezing or crystallization temperature of the water likely to be in suspension in the ambient gas, and in that the circuit also comprises at least: one dehydrating filter positioned downstream from the first portion of the circuit relatively to the direction of motion of the ambient gas in the nozzle, in order to drive the gas which has carried out a heat transfer towards the refrigerant fluid of the first portion of the circuit, and one fourth portion of the circuit forming an evaporation tank positioned so as to be in contact with the air moving in the nozzle, intended to allow evaporation of the refrigerant fluid at a clean evaporator by carrying out a heat exchange towards the refrigerant fluid at temperatures below the freezing or crystallization temperature of the water in suspension in the ambient gas, this fourth portion being positioned downstream from the dehydrating filter relatively to the direction of movement of the ambient gas in the nozzle.
 3. The heat engine according to claim 1, the fluid capable of absorbing heat in the liquefier is formed by a coolant fluid moving in a clean closed circuit which allows absorption of heat of the refrigerant fluid at the liquefier on the one hand and provision of heat to a refrigerant fluid intended to be evaporated at an evaporator on the other hand.
 4. The heat engine according to claim 1, the fluid capable of absorbing heat in the liquefier is formed by the refrigerant fluid moving in a parallel portion of the circuit and flowing from a fourth or fifth portion of the circuit forming an evaporation tank positioned so as to be in contact with the fluid, outside the engine, moving in the nozzle, intended to allow evaporation of the refrigerant fluid at a clean evaporator, this fourth or fifth portion being positioned downstream from the first portion of the circuit relatively to the direction of motion of the outer fluid in the nozzle, the refrigerant fluid evaporating at a temperature below the temperature of the refrigerant fluid flowing from the tank of the first portion being set into motion by a compressor positioned downstream from the liquefier relatively to the direction of motion of the fluid in the circuit.
 5. The heat engine according to claim 1, the engine integrates at least one auxiliary heating device in order to increase the temperature of the refrigerant fluid at the outlet and/or at the inlet of at least one turbine and/or compressor, and in that the auxiliary heating device is associated with a device for injecting liquid refrigerant fluid in order to maintain a saturating vapor pressure and avoid the formation of a dry vapor.
 6. The heat engine according to claim 1, at least one component capable of operating with heat losses is positioned in an adiabatic enclosure open in the portion of the nozzle located upstream from at least the first portion of the circuit relatively to the direction of motion of the outer fluid in the nozzle.
 7. The heat engine according to claim 1, the motion of the fluid, outside the engine, in the nozzle, involves a turbo-compressor.
 8. A method for operating a heat engine according to claim 1, the method comprises cyclically: a step for vaporizing the refrigerant fluid in a tank of a first portion of the circuit subsequent to at least one heat transfer from a fluid outside the engine, a suction step by a compressor of the refrigerant fluid vaporized in a tank of a first portion of the circuit, a step for actuating a power turbine by displacing the refrigerant fluid vaporized in the circuit, a step for liquefying the refrigerant fluid in the second portion of the circuit forming the liquefier subsequent to at least one heat transfer towards a fluid used as a coolant, a step for returning the liquefied refrigerant fluid into a tank of the first portion of the circuit.
 9. The method for operating a heat engine according to claim 8, the fluid used as a coolant being the refrigerant fluid moving in a parallel portion of the circuit, the method also comprises: a step for vaporizing the refrigerant fluid in a tank of a fourth or fifth portion of the circuit subsequent to at least one heat transfer from a fluid outside the engine concomitantly with the step of vaporization of the refrigerant fluid in the first portion of the circuit, the vaporization being carried out at a temperature less than that of the vaporization in the first portion of the circuit, a step for suction by the compressor of the refrigerant fluid vaporized in a tank of a fourth or fifth portion of the circuit, a step for absorption of heat from the refrigerant fluid during liquefaction in the liquefier by the refrigerant fluid vaporized in a tank of a fourth or fifth portion of the circuit, a step for mixing, at the compressor, the refrigerant fluid vaporized in a tank of a fourth or fifth portion of the circuit, with the vaporized refrigerant fluid in another portion of the circuit in order to integrate the circuit of the vaporized refrigerant fluid into the first portion of the circuit, and a step for returning the liquefied refrigerant fluid into a tank of the fourth or fifth portion of the circuit.
 10. The method for operating a heat engine according to claim 8, the method also comprises at least: one step for heating the evaporated refrigerant fluid moving in the circuit, and/or one step for injecting liquefied refrigerant fluid into evaporated refrigerant fluid moving in the circuit. 